The present invention relates to a device in connection with a reel-up of a web. The invention also relates to a method in connection with a reel-up of a web.
Reel-ups of web-like materials are used for reeling a material passed in a continuous web into a tight reel, so that it can be transferred to further processing. In the reel-ups of a paper web, a continuous paper web passed from a paper machine, a coating machine or corresponding paper processing apparatus is reeled around a reeling axle i.e. a reel, spool, to form a reel. For example in a so-called Pope-reeler, or in a center-drive assisted Pope-reeler, the finished paper is reeled around a reeling axle. The web is passed on the reel via a reeling cylinder rotatably arranged, against which the reeling axle is loaded by means of a loading device located in connection with the reeling axle.
The web is passed to the reeling axle via a nip formed between the preceding layers of the reel and the mantle surface of the reeling cylinder. At this point where the web enters in contact with the preceding layers of the reel, the web is, due to the aforementioned loading device, affected by a particular nip load, linear pressure. In present-day reel-up types, the reeling nip between the reeling cylinder and the reel primarily prevents the access of air into the reel. By controlling the loading exerted on the web it is, however, also possible to control the tightness of the reel that is being formed, and in addition to this, the aim is to change the loading during the reeling, so that the tightness of the reel would comply with the quality requirements set by the paper grade and the finishing process in different sections in the radius of the reel. The reeling process is controlled indirectly by adjusting the reeling parameters (e.g. linear load, web tension, peripheral force and reeling force). The adjustment is typically conducted with a special program. The main objective of the reeling is to reel a continuous paper web to form a reel which fulfills the requirements imposed thereupon by the reeling process and further processing with respect to processibility and thereby the structure of the reel as well as the paper quality.
When the old reel has become full, the web has to be cut and the winding of the web following the cut-off point around a new reeling axle has to be started. In practice, this takes place in such a way that when the paper roll formed around the reeling axle has accumulated into its full size, a new empty reel is transferred, typically simultaneously and from above the reeling cylinder, onto the surface of the reeling cylinder, while the paper web is left therebetween. The full paper reel is transferred away from the reeling cylinder, and thereafter the paper web is cut with a suitable way and the end of the web following the cut-off point is guide d onto the perimeter of an empty reeling axle, onto which the new web begins to accumulate to form a reel. Thereafter the new reeling axle is transferred to a reeling carriage, travelling on separate linear guides, or on top of horizontal reeling rails. The reel that has become full is transferred e.g. by means of a transfer device along the reeling rails to an unloading station, and at the same time a new reeling axle is brought onto the reeling rails. During the initial reeling process the loading is controlled by means of force devices of the initial reeling device, and when the reeling axle has been transferred e.g. to the reeling carriage, the loading is controlled by means of force devices coupled to the reeling carriage, typically by means of pressurized medium operated actuators, i.e. cylinders.
For example U.S. Pat. No. 4,634,068 discloses a reeling apparatus equipped with force devices of the initial reeling device, i.e. with a separate loading cylinder and a relief cylinder, and when the reeling axle is on the reeling rails, with a loading cylinder which presses the axle against the reeling cylinder. The used loading cylinder is coupled e.g. to swinging arms turnably articulated in the frame of the reel-up. By means of the relief cylinders it is possible to compensate for the effects of gravity on the reeling cylinder, and thus these are used for so-called profiling. Typically in the initial reeling device the loading, relieving and the adjustment of the position of the reeling axle with respect to the reeling cylinder are conducted by means of one double-acting pressurized medium operated cylinder. In the reel-up the loading force is determined by measuring the angular position of the swinging arms. The loading force is adjusted by means of an actuator coupled to the swinging arm.
In a control circuit of a reel up, which is disclosed in the U.S. Pat. No. 5,285,979, the loading takes place by means of a carriage moving in the frame of the reel-up along linear guides, to which carriage the loading force device is connected. In the publication the reeling axle is arranged in a swinging arm turnably journalled to the carriage, which swinging arm, however, remains stationary during the loading and is only used when the full reel is removed by turning the swinging arms to the direction of removal with special removal cylinders. The aforementioned force device is used to supply the desired loading force or to transfer the reeling axle further away from the reeling cylinder as the size of the reel grows. The actual loading force is affected by many factors such as the friction produced by the motion of the force device as well as the kinetic friction of the structure supporting the reeling axle when it is moved. The loading force is measured in the device with sensor means arranged in connection with the swinging arm.
There are also known reel-ups such as the one presented in EP patent 604558 and in the related U.S. Pat. No. 5,393,008. The patent discloses carriages arranged which are linearly movable in guides parallel to the reeling rails, the position of the carriages being determined on the basis of hydraulic cylinders coupled between the frame of the reel-up and the carriages. Thus, by means of these hydraulic cylinders, the location of the reeling axle is at the same time also adjusted with respect to the reeling cylinder. The carriages are provided with separate pressing devices which press the bearing housings located at the ends of the reeling axle and resting on the reeling rails with an adjustable force towards the reeling cylinder to produce the necessary nip pressure. On the other side of the bearing housing, the carriages are also provided with positioning devices by means of which the location of the reeling axle in the carriage can be adjusted more accurately. The loading force is measured in the device with sensor means arranged in connection with the pressing device.
The publication EP 0 79 829 A2 discloses a reeling device in which the reeling cylinder is arranged in a moving carriage which is also provided with a pressurized medium operated cylinder to function as a force device to effect a loading between the reeling cylinder and the reel. The carriage can be moved by means of separate actuators.
In the above-described cases, to control e.g. the reeling carriage, the initial reeling device and the loading device, hydraulic cylinders are typically used in pairs to control the different ends of the reeling axle. Thus, the control of the ends is arranged for example by means of an integrated carriage or a carriage arranged in connection with each end to move independently.
In the above-described device the act of measuring the loading force of the nip is, however, arranged in a manner which is affected disturbingly by frictions due to the function of the device, such as rolling frictions, sliding frictions and other mechanical disturbances occurring in the members used for measurement.
In addition, in the above-described devices, separate apparatuses are used for adjusting both the loading force by controlling the pressure of the force devices and e.g. the position of said carriages by controlling the actuators. This results in a complicated control process and requires a considerable accuracy and reliability especially from the pressure adjustment.
It is an aim of the present invention to eliminate the drawbacks of prior art and to present a simple and reliable device to be used in connection with a reel-up, for example to control the loading, i.e. so-called nip load, between a reeling cylinder and a reeling axle which is placed in the transfer carriage of the reel-up and controlled by means of separate carriages from its ends and located in the initial reeling device or placed on reeling rails, or to control the distance between the same or the mutual position of the same by means of pressurized medium operated cylinders. It is a central principle of the invention to apply an elastic element that stores energy.
It is a considerable advantage of the device according to the present invention that it is possible to implement the adjustment of the loading force in a very simple manner by means of position adjustment, conducted with actuators functioning as force devices, wherein it is possible to avoid pressure adjustment. This makes the construction of the sensor means required in the reel-up considerably more simple, and facilitates the adjustment to be conducted. Advantageously, the loading and the positioning is taken care of by a pair of pressurized medium operated cylinders. Another advantage of the invention is that by directly measuring the dimension changing according to the loading force of the element, especially the disturbing effects of the friction forces affecting the measurement are avoided. Furthermore, it is an advantage of a preferred embodiment of the invention that the element is independent of an external power source, wherein it utilizes only the energy stored therein. The energy is stored in the element in a very simple manner for example by compressing it in connection with the position adjustment.